This invention relates generally to angle and distance measuring devices and more particularly to a transparent disk protractor which can be used for many purposes.
An ordinary protractor of the simplest type known heretofore is in the form of a plate of semicircular shape and is used principally for measuring and laying down angles. The only other use to which this simple protractor can be put is measurement of short distances by means of a linear scale provided along the straight-line edge thereof. Known also are protractors comprising a plurality of parts, such as bevel protractors, multiple-arm protractors, and protractors in combination with straight-edges, as in drafting machines. These protractors tend to be of relatively complicated structure requiring precision in fabrication and, being relatively heavy, are not as "handy" as a simple, single-member protractor.